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JPanel没有显示出来。

javaswingjpanel
4

JPanel没有显示出来，我已经使用.setVisible方法，但是它仍然不显示。它已经被构建了，但是没有显示出来。我在编程的这个部分只是一个初学者。

    package calculatorv3;


    public class CalculatorForm extends javax.swing.JPanel {
        private static final long serialVersionUID = 1L;


       public CalculatorForm() {
            initComponents();
       }

        /**
         * This method is called from within the constructor to initialize the form.
         * WARNING: Do NOT modify this code. The content of this method is always
         * regenerated by the Form Editor.
         */
        @SuppressWarnings("unchecked")

        private void initComponents() {

            jTextField2 = new javax.swing.JTextField();
            jTextField3 = new javax.swing.JTextField();
            jTextField4 = new javax.swing.JTextField();
            jButton2 = new javax.swing.JButton();
            jButton3 = new javax.swing.JButton();
            jButton4 = new javax.swing.JButton();
            jButton5 = new javax.swing.JButton();
            jButton6 = new javax.swing.JButton();
            jButton7 = new javax.swing.JButton();
            jButton8 = new javax.swing.JButton();
            jButton9 = new javax.swing.JButton();
            jButton10 = new javax.swing.JButton();
            jButton11 = new javax.swing.JButton();
            jButton12 = new javax.swing.JButton();
            jButton13 = new javax.swing.JButton();
            jButton14 = new javax.swing.JButton();
            jButton15 = new javax.swing.JButton();
            jButton1 = new javax.swing.JButton();
            jButton16 = new javax.swing.JButton();
            jButton17 = new javax.swing.JButton();

            jButton2.setText("2");
            jButton2.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton2ActionPerformed(evt);
                }
            });

            jButton3.setText("1");
            jButton3.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton3ActionPerformed(evt);
                }
            });

            jButton4.setText("3");
            jButton4.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton4ActionPerformed(evt);
                }
            });

            jButton5.setText("4");
            jButton5.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton5ActionPerformed(evt);
                }
            });

            jButton6.setText("5");
            jButton6.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton6ActionPerformed(evt);
                }
            });

            jButton7.setText("6");
            jButton7.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton7ActionPerformed(evt);
                }
            });

            jButton8.setText("7");
            jButton8.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton8ActionPerformed(evt);
                }
            });

            jButton9.setText("8");
            jButton9.addActionListener(new java.awt.event.ActionListener() {
                public void actionPerformed(java.awt.event.ActionEvent evt) {
                    jButton9ActionPerformed(evt);
                }
            });

            jButton10.setText("9");

            jButton11.setText("0");

            jButton12.setText("Add");

            jButton13.setText("Sub");

            jButton14.setText("Mul");

            jButton15.setText("Div");

            jButton1.setText("Enter");

            jButton16.setText("Reset");

            jButton17.setText("Equals");

            javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
            this.setLayout(layout);
            layout.setHorizontalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                        .addComponent(jTextField2)
                        .addComponent(jTextField3)
                        .addComponent(jTextField4)
                        .addGroup(layout.createSequentialGroup()
                            .addComponent(jButton3)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                            .addComponent(jButton2)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                            .addComponent(jButton4)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(jButton5)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                            .addComponent(jButton6)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                            .addComponent(jButton12)
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                            .addComponent(jButton14))
                        .addGroup(layout.createSequentialGroup()
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                                .addGroup(layout.createSequentialGroup()
                                    .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                    .addComponent(jButton16, javax.swing.GroupLayout.PREFERRED_SIZE, 113, javax.swing.GroupLayout.PREFERRED_SIZE))
                                .addGroup(layout.createSequentialGroup()
                                    .addComponent(jButton7)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                    .addComponent(jButton8)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                    .addComponent(jButton9)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(jButton10)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                    .addComponent(jButton11)))
                            .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                            .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                                .addGroup(layout.createSequentialGroup()
                                    .addComponent(jButton13)
                                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                    .addComponent(jButton15)
                                    .addGap(0, 0, Short.MAX_VALUE))
                                .addComponent(jButton17, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
                    .addContainerGap())
            );
            layout.setVerticalGroup(
                layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                .addGroup(layout.createSequentialGroup()
                    .addContainerGap()
                    .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                    .addGap(7, 7, 7)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jButton3)
                        .addComponent(jButton2)
                        .addComponent(jButton4)
                        .addComponent(jButton5)
                        .addComponent(jButton6)
                        .addComponent(jButton12)
                        .addComponent(jButton14))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jButton7)
                        .addComponent(jButton8)
                        .addComponent(jButton9)
                        .addComponent(jButton10)
                        .addComponent(jButton11)
                        .addComponent(jButton13)
                        .addComponent(jButton15))
                    .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                    .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                        .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                        .addComponent(jButton17, javax.swing.GroupLayout.DEFAULT_SIZE, 40, Short.MAX_VALUE)
                        .addComponent(jButton16))
                    .addContainerGap())
            );
        }// </editor-fold>

        private void jButton2ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton3ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton4ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton5ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton6ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton7ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton8ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        private void jButton9ActionPerformed(java.awt.event.ActionEvent evt) {
            // TODO add your handling code here:
        }

        // Variables declaration - do not modify
        private javax.swing.JButton jButton1;
        private javax.swing.JButton jButton10;
        private javax.swing.JButton jButton11;
        private javax.swing.JButton jButton12;
        private javax.swing.JButton jButton13;
        private javax.swing.JButton jButton14;
        private javax.swing.JButton jButton15;
        private javax.swing.JButton jButton16;
        private javax.swing.JButton jButton17;
        private javax.swing.JButton jButton2;
        private javax.swing.JButton jButton3;
        private javax.swing.JButton jButton4;
        private javax.swing.JButton jButton5;
        private javax.swing.JButton jButton6;
        private javax.swing.JButton jButton7;
        private javax.swing.JButton jButton8;
        private javax.swing.JButton jButton9;
        private javax.swing.JTextField jTextField2;
        private javax.swing.JTextField jTextField3;
        private javax.swing.JTextField jTextField4;
        // End of variables declaration

        public static void main(String args[]) {
            java.awt.EventQueue.invokeLater(new Runnable() {
                @Override
                public void run() {
                    new CalculatorForm().setVisible(true);
                }
            });
        }

        }

我找不出代码中的问题，不要在意排版错误“按钮编号”，我只关心如何显示面板

好的，我已经编辑了这段代码，将其与public static void main合并，只需要初始化一次

import javax.swing.JButton; import javax.swing.JTextField;

/*
 * To change this template, choose Tools | Templates
 * and open the template in the editor.
 */

/**
 *
 * @author Jfetizanan
 */
public class NewMain {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {

        JTextField jTextField2 = new javax.swing.JTextField();
        JTextField jTextField3 = new javax.swing.JTextField();
        JTextField jTextField4 = new javax.swing.JTextField();
        JButton jButton2 = new javax.swing.JButton();
        JButton jButton3 = new javax.swing.JButton();
        JButton jButton4 = new javax.swing.JButton();
        JButton jButton5 = new javax.swing.JButton();
        JButton jButton6 = new javax.swing.JButton();
        JButton jButton7 = new javax.swing.JButton();
        JButton jButton8 = new javax.swing.JButton();
        JButton jButton9 = new javax.swing.JButton();
        JButton jButton10 = new javax.swing.JButton();
        JButton jButton11 = new javax.swing.JButton();
        JButton jButton12 = new javax.swing.JButton();
        JButton jButton13 = new javax.swing.JButton();
        JButton jButton14 = new javax.swing.JButton();
        JButton jButton15 = new javax.swing.JButton();
        JButton jButton1 = new javax.swing.JButton();
        JButton jButton16 = new javax.swing.JButton();
        JButton jButton17 = new javax.swing.JButton();

        jButton2.setText("2");
        jButton2.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton3.setText("1");
        jButton3.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton4.setText("3");
        jButton4.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton5.setText("4");
        jButton5.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton6.setText("5");
        jButton6.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton7.setText("6");
        jButton7.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton8.setText("7");
        jButton8.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton9.setText("8");
        jButton9.addActionListener(new java.awt.event.ActionListener() {
            @Override
            public void actionPerformed(java.awt.event.ActionEvent evt) {

            }
        });

        jButton10.setText("9");

        jButton11.setText("0");

        jButton12.setText("Add");

        jButton13.setText("Sub");

        jButton14.setText("Mul");

        jButton15.setText("Div");

        jButton1.setText("Enter");

        jButton16.setText("Reset");

        jButton17.setText("Equals");

        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);
        layout.setHorizontalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                    .addComponent(jTextField2)
                    .addComponent(jTextField3)
                    .addComponent(jTextField4)
                    .addGroup(layout.createSequentialGroup()
                        .addComponent(jButton3)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton2)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton4)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jButton5)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                        .addComponent(jButton6)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton12)
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addComponent(jButton14))
                    .addGroup(layout.createSequentialGroup()
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING, false)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jButton16, javax.swing.GroupLayout.PREFERRED_SIZE, 113, javax.swing.GroupLayout.PREFERRED_SIZE))
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jButton7)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jButton8)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jButton9)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jButton10)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                                .addComponent(jButton11)))
                        .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                        .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
                            .addGroup(layout.createSequentialGroup()
                                .addComponent(jButton13)
                                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.UNRELATED)
                                .addComponent(jButton15)
                                .addGap(0, 0, Short.MAX_VALUE))
                            .addComponent(jButton17, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE))))
                .addContainerGap())
        );
        layout.setVerticalGroup(
            layout.createParallelGroup(javax.swing.GroupLayout.Alignment.LEADING)
            .addGroup(layout.createSequentialGroup()
                .addContainerGap()
                .addComponent(jTextField2, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField3, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addComponent(jTextField4, javax.swing.GroupLayout.PREFERRED_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.PREFERRED_SIZE)
                .addGap(7, 7, 7)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton3)
                    .addComponent(jButton2)
                    .addComponent(jButton4)
                    .addComponent(jButton5)
                    .addComponent(jButton6)
                    .addComponent(jButton12)
                    .addComponent(jButton14))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton7)
                    .addComponent(jButton8)
                    .addComponent(jButton9)
                    .addComponent(jButton10)
                    .addComponent(jButton11)
                    .addComponent(jButton13)
                    .addComponent(jButton15))
                .addPreferredGap(javax.swing.LayoutStyle.ComponentPlacement.RELATED)
                .addGroup(layout.createParallelGroup(javax.swing.GroupLayout.Alignment.BASELINE)
                    .addComponent(jButton1, javax.swing.GroupLayout.DEFAULT_SIZE, javax.swing.GroupLayout.DEFAULT_SIZE, Short.MAX_VALUE)
                    .addComponent(jButton17, javax.swing.GroupLayout.DEFAULT_SIZE, 40, Short.MAX_VALUE)
                    .addComponent(jButton16))
                .addContainerGap())
        );

    }
}

但是这个会显示错误，你想怎么处理？
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(this);
        this.setLayout(layout);

如何将所有对象添加到框架中

好的，我终于完成了代码... 在这里，谢谢。

程序本身...

在编写JPanel时，不需要使用setVisible方法，因为当它被添加到父组件中时，默认情况下会自动显示。 - Harmeet Singh
嗯，如何初始化“public CalculatorForm()”？ - JFetz2191
在这里放什么？ public static void main(String args[]) { java.awt.EventQueue.invokeLater(new Runnable() { @Override public void run() { } }); - JFetz2191
顺便提一下，当你遇到 GUI 的问题时，请在仅涉及 1 或 2 个按钮而非 17 个按钮、4 个文本字段的情况下提问。开发代码的基本原则是“经常编译和运行 - 如果出现无法从自己的研究中回答的问题，请第一时间提问”。 - Andrew Thompson
1个回答
8

这是不正确的

public class CalculatorForm extends javax.swing.JPanel

应该是这样的

public class CalculatorForm extends javax.swing.JFrame

这里是一个正确的方式：如何制作框架。
更新： 按照您正在进行的操作，在initComponents()中执行。
JPanel panel = new JPanel();
javax.swing.GroupLayout layout = new javax.swing.GroupLayout(panel);
panel.setLayout(layout);
add(panel);

更新：这是正确的做法

public class CalculatorForm {

    private static final long serialVersionUID = 1L;

    public CalculatorForm() {
        initComponents();
    }

    private void initComponents() {
        JFrame frame = new JFrame();
        // frame settings like size, close operation etc.
        JPanel panel = new JPanel();
        // init textfields and buttons
        // add listeners or whatever
        javax.swing.GroupLayout layout = new javax.swing.GroupLayout(panel);
        panel.setLayout(layout);
        // layout settings goes here
        frame.add(panel);
        frame.setVisible(true);
    }
    public static void main(String args[]) {
        java.awt.EventQueue.invokeLater(new Runnable() {
            @Override
            public void run() {
                new CalculatorForm();
            }
        });
    }
}
1
（或者它应该添加到一个框架中） - MadProgrammer
1
第一个可能不太明智（扩展一个没有必要扩展的组件），但并不是“错误”的。通过将 new CalculatorForm().setVisible(true); 更改为 JOptionPane.showMessageDialog(null, new CalculatorForm()); 可以看到 GUI。 - Andrew Thompson
@AndrewThompson 先生，是的，我已经阅读了您在大多数评论和答案中提到的extends JFrame或任何其他Component不应该被使用，但是考虑到OP的需求，我发布了这个快速解决方案。 - Harmeet Singh
@AndrewThompson “先生”，这是对您的尊称。 - Harmeet Singh
1
我知道这是你的本意，但它让我想起了在学校被老师要求称呼他们为“先生”的不愉快经历。那些老师并不值得尊重，在我看来从未赢得过“加一分”。所以，只用“安德鲁”就可以了，谢谢哈米特。 - Andrew Thompson
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